I will selfishly (but accurately) claim I pioneered a new line of thinking or "theory" as to why leftists and (especially) feminists are ugly. In it's most refined and reduced form it is:
"Feminists and leftists are uglier than their conservative counterparts because maintaining physical beauty requires work, effort, and rigor; things antithetical to their leftist political ideology which entails laziness, the avoidance of rigor, and the least amount of effort."
Dalrock came up with a very interesting alternative, though not mutually-exclusive theory:
Feminists are miserly with their love.
Love is selflessness. Putting somebody ahead of your own self. And feminists are indeed a very selfish and self-centered lot. I've pointed it out before and I'll point it out again, the Manosphere is infinitely more loving than feminists in that we actually care about what women want. So much so we advocate lifting weights, losing weight, eating healthy, etc. Whereas I ask, when is the last time you heard a feminist advocate staying skinny, getting implants, or cook a meal to make their man happy? It's simple - they don't. Matter of fact, they go the opposite direction and advocate such bullshit as "fat acceptance" and dare to lecture men to have the audacity to like what they are genetically programmed to.
This is why they tend not to be pretty. Because "pretty" is an outward, outside, and selfless quality observed by OTHER PEOPLE. A kindness or a courtesy you give to your fellow man (and woman) to:
maintain your physical shape
do yourself up and
just plain give a damn about your appearance.
But since feminists are so self-centered and are incapable of selflessness, they don't care what other people think. They are incapable of empathy. They are only capable of focusing on themselves. And when somebody is so myopic and only care about themselves, then they are incapable of presenting beauty to other people. Ergo, why most feminists tend to be ugly.
The two theories are actually the same, but I like Dalrock's view in that it shows you just what lonely, sad, pathetic and dysfunctional lives these women are living. They are incapable of considering others. They are incapable of love. And it is the fear of effort, rigor and work that keeps them from enjoying the best life has to offer.
Oh well, you feminists enjoy the decline.